The invention relates to a dispenser cathode, particularly to a metal capillary cathode, for electric discharge vessels with an emission substance carrier disk which is porous on the front face, and comprises a metal melting at a high temperature, such as tungsten.
Cathodes for electric discharge vessels are known in which, during operation, emission substances migrate from an emission substance supply to the cathode surface through fine openings of a porous emission substance carrier covering this emission substance supply and consisting particularly of porous, sintered metal melting at a high temperature such as, for example, tungsten and in which the supply for emitting barium during operation consists of barium oxide (German L.P. No. 1217 503).
Such cathodes are employed, for example, in traveling wave tubes and in disk-seal tubes (lighthouse tubes).
The known dispenser cathodes, however, have the disadvantage that, during operation, electrons are emitted not only from the front face but also from the side faces.